First Teen Mom Catelynn Lowell turned 21 and now it's Teen Mom Kailyn Lowry's turn! The star of the MTV reality show and mom to son Isaac is officially allowed to have her first drink today and place her first bet -- a milestone if ever there was one. Kailyn tweeted that she's having a great day and woke up the best way possible -- she shared a photo that showed off her 28 unread birthday text messages. Aw.

After she gets through reading those, we hope she takes her fine self out on the town. Kailyn's got some killer style that's evolved nicely over the years -- a party dress, a sock bun, and some hot sneakers might be the perfect birthday outfit for this girl.

In honor of her big day, check out 5 of Kailyn's best looks over the years, and see how far she's come. Feels like only yesterday when she was 18!